Catalog
Introduction
In layman's terms, a relay is an electromagnetic switch that is typically used to switch the power supply either automatically or manually. In this post, I'll go over the fundamentals of 4 and 5 pin relay wiring diagrams. The relay comes in a variety of shapes and sizes. It can be based on the pins or contacts, ampers, or voltage ratting (AC or DC). These contacts are pins 4, 5, 8, 11, 14, and so on. However, we have two coil pins on each pin. Where we supply the necessary ratting current. As an example, suppose we have a 12-volt DCV relay. As a result, we will supply 12 volts of DC (Direct current) to the relay coil. And if we have the 220 ACV, we can supply the relay coil with 220 volts AC (alternating current).
The remaining pins and contacts are known as main contacts or switching contacts. The relay switching pins include the following: common, NC (normally open), and NO (normally close).
Ⅰ How to Wire a Relay?
How To Wire A Relay - Quick Tip
Still confused? See the full video here.
Ⅱ Why Use a Relay?
There are several reasons why you might need or want to use a relay:
Using a lower current circuit to replace a high current circuit.
This is the most common reason, and it is useful when an in-line switch or existing circuit cannot handle the required current. For example, if you wanted to install some high-powered work lights that activate with the headlights, there's a chance they'd exceed the capacity of the existing loom.
Cost Saving
Because high current capacity wiring and switches are more expensive than lower current capacity versions, using relays reduces the need for more expensive components.Activating more than one circuit from a Single Input
A single input signal from one part of an electrical system (e.g., central locking output, manual switch, etc.) can be used to activate one or more relays, which then complete one or more other circuits, allowing you to carry out multiple functions from a single input signal.
Carrying Out Logic Functions
When linked together, electromagnetic relays can be used to perform logical operations based on specific inputs (for example, latching a +12V output on and off from a momentary input, flashing alternative left and right lights, and so on). Although electronic modules have largely replaced these logical functions in OEM designs, it can still be useful, fun, and often more cost-effective to use relays to perform them in some after-market projects (particularly where you have a bespoke application).
Ⅲ Relay Wiring Diagram
A simple wiring diagram of a relay is shown here to help you understand how it works in a circuit.
Relay wiring diagram
Let's talk about this relay wiring diagram now.
It is the relay that is powered by the DC supply. Pin 1 is the magnetic coil's positive pin. Pin 2 is the coil's negative pin. As a result, we used an SPST switch to connect a DC power source across terminals 1 and 2. We can use this switch to turn on or off the power supply to the relay coil whenever we want.
Terminal 3 is shared by NO and NC contacts. Terminal 5 is designated as NO, while Terminal 4 is designated as NC. This means that under normal circumstances, terminal 3 is connected to terminal 4. When we apply power to the coil, terminal 3 is connected to terminal 5.
As you can see, we connected two LEDs here. The NO terminal is connected to the red LED, and the NC terminal is connected to the green LED. So, under normal circumstances, the green LED will glow, but when we apply power to the relay by turning on the switch, the red LED will glow.
Ⅳ 4 Pin Relay Wiring Diagram vs 5 Pin Relay Wiring Diagram
4.1 The Main Difference between 4 or 5 Pin Relays
A 4 pin relay controls a single circuit, whereas a 5 pin relay switches power between two circuits.
4 Pin Relay
2 pins (85 & 86) control the coil and 2 pins (30 & 87) switch power on a single circuit in a 4 pin relay. Four-pin relays are available in two configurations: normally open and normally closed. When the coil is activated, a normally open relay turns on the power to a circuit. When the coil is activated, a normally closed relay turns off the power to the circuit.
5 Pin Relay
5 pin relays have two pins (85 & 86) for controlling the coil and three pins (30, 87 & 87A) for switching power between two circuits. They have connection pins that are both normally open and normally closed. Power is switched from the normally closed pin to the normally open pin when the coil is activated.
4.2 4 Pin Relay Wiring Diagram
The diagram of a four-pin relay is depicted in the image below. This circuit diagram will be used later to wire a relay for driving lights.
4 Pin Relay Wiring Diagram
You'll need to use a fuse to connect the relay's Pin 30 to the 12V battery for driving lights. We're not directly connecting pin 30 to the battery here; instead, we're using a fuse. This is because the fuse protects us from overcurrents.
If there is a fault in the driving light circuit, the fuse protects the burning of lights and other circuits from current overshoots.
Pin 85 of the relay is grounded, while Pins 87 and 86 are switching pins. You can turn on the main beams of the driving light using this 4 pin relay by switching the battery connections to either circuit connected with pin 86 or 87 of the relay.
4.3 Sample Wiring Diagrams for a 4 Pin Normally Open Relay
Sample Wiring Diagrams for a Normally Open Relay
Example 1. 4 pin (normally open) relay with the switch on the control circuit's positive side.
Example 2. 4 pin (normally open) relay with the switch on the control circuit's negative side.
Note: These circuits have been simplified to demonstrate the function of a relay and thus do not include the fuse protection that would be required. Relay coil terminals have no polarity unless the relay coil is protected by a diode (inside the relay), in which case the coil terminal wired to the diode's anode must be connected to negative.
4.4 Why to Use a 4 Pin Relay for Driving Lights
The main reason for installing this relay system is to keep dangerous voltages outside of your cabin or driving area.
The high voltage required by your headlight, which is supplied by the battery, is kept inside the engine compartment by a relay.
Simply put, a relay is a switch that is controlled by another switch. The switch installed in the vehicle's sitting cabin, on the front side of the driver, operates on very low voltage. As you can see, this voltage is not high enough to harm the driver or other electronic components. This switch provides power to the relay, which is essentially an electromagnet. It will also control the high current circuit that is directly connected to the headlights.
This is how a low current circuit controls a high current circuit, keeping both the driver and the car electronics safe, and why we need a relay in our headlights!
4.5 5 Pin Relay Wiring Diagram
A pin relay is SPDT relay, which means that the contacts of relay single pole double throw. In single pole double throw relay, we have one pin is common, 2nd are normally close and 3rd are normally open. Two pins for the coil. This relay can be used for different types of controlling or switching. Such as for lights, fan, fuel pump, etc. Here I showed the 5 pin relay wiring diagram.
5 pin relay wiring diagram
In the diagram above, I've depicted a single pole double throw relay (5 pin relay). Not that his relay can be 5 volts DCV, 12 volts DCV, 24 volts DCV, and so on, depending on the coil's ratting voltage. In the above 5 pin relay diagram, pins 1 and 2 are for the coil, pin 3 is the common pin, pin 4 is normally closed, and pin 5 is normally open.
4.6 How to Use 5 Pin Relay
A relay can be used for a variety of switching purposes. If you want to control electrical devices automatically, a relay is the best option. When we talk about relays, as I previously stated, there are various types of relays for various applications. This post, however, is about the 5 pin relay. As illustrated by the 5 pin relay diagram. This has three main pins. As opposed to a single pole double throw.
So when we say single pole double throw, we mean that it has a common point as well as two other points (NC and NO).
To switch something from a single pole double throw relay, you must use the common and other points. For example, if you require that the light bulb be turned off when the relay operates. Then you must use a common, normally closed pin. If you want to turn on the light bulb, you must use the common and normally open pins. I've shown how to wire a 5 pin relay for lights in this article.
4.7 5 Pin Relay Wiring Diagram for lights
In the 5 pin relay wiring diagram below, I show how to turn on lights when the relay is activated and how to turn them off when the relay is deactivated.
Similarly, if you want to control or wire a fan with a relay, you can use the same method. It is important to note that the ratted voltage must be applied to the relay coil. If your relay is powered by 12 volts DCV. Then you must supply the 12-volt DCV.
Ⅴ FAQ
1. What costs more than lower current capacity versions?
High current capacity wiring and switches.
2. What can you use to activate one or more relays?
A single input from one part of an electrical system.
To activate one or more relays that then complete one or more other circuits and so carry out multiple functions from one input signal.
4. What will switch power on for a circuit when the coil is activated?
A normally open relay.
5. What is the main purpose of installing a 4 Pin Relay for Driving Lights?
To keep dangerous voltages outside of your cabin or driving place.